Audio systems recreating multi-channel sound has become popular in the last decade and in particular consumer sound systems such as surround sound systems have become prevalent, e.g. for use in Home Theatre Systems.
However, a perceived disadvantage of such systems is the impracticability of having to place a relatively large number of speakers at different locations to generate the desired sound space. Indeed, for most consumers, situating several large speakers in a room in order to reproduce convincing multi-channel sound is not always desirable or feasible (visual impact, cables, absence of suitable locations for the speakers etc). Indeed, speakers are often considered unsightly and therefore systems have been developed which seek to minimize the visual impact of the speakers by making these as small as possible. Specifically, systems have been developed wherein lower frequencies are fed to a subwoofer which is common for all channels whereas the higher frequencies are produced by individual satellite speakers for each channel. As the satellite speakers need only reproduce the higher frequencies they can be made substantially smaller.
However, the speakers are still of a size where they tend to be noticeable and therefore it is desired to further reduced the size of these speakers. Also, in order to achieve a sufficiently high audio quality from the speakers, relatively high quality speakers must be used thereby adding cost to the system. Furthermore, the reduction in speaker size is often limited by the desired audio quality and many systems using small speakers tend to have a relatively low audio quality.
Specifically, the bandwidth covered by the satellite speakers currently extends down to a relatively low frequency of around 100 Hz-150 Hz (allowing the subwoofer to render the lower frequency signals) which tends to require relatively large speakers for high quality sound reproduction. Furthermore, although size and cost may be reduced by a higher cut-off frequency of e.g. 200 Hz or higher, this tends to result in a reduced audio quality of the system as a whole as a higher proportion of the frequency band is supported by the subwoofer.
Specifically, this tends to reduce the spatial perception and to reduce the perceived sound stage for the multi-channel system. For example, sound objects, such as voices, tend to be perceived as being heard partly through the subwoofer for the lower tones and partly through the satellites for the higher tones. This may result in both a perceived change of location of the sound objects as well as a reduced sound stage or spatial perception as a whole.
Furthermore, in order to generate sufficiently high sound levels from the satellite speakers a relatively high power level tends to be required for each satellite speaker.
Hence, an improved multi-channel audio system would be advantageous and in particular a system allowing reduced speaker size, reduced power consumption, reduced speaker cost, improved audio quality, improved spatial perception, facilitated implementation and/or improved performance would be advantageous.